Purification of alkyl phenols



ties such as organic sulfur.

Fetented eta 2 l4 si s ' FFEZQE Eerlseley, ilallilt, assistants to Smell Development @emneny, San Francisco, @elifi, e corporation oi welcome l lo Drawing, llnnlleetion July 13, will,

Selle-l No. 345,376

ill see-set) 11 Claims.

Tots invention relates to the desuliurization of el'syl phenols by treating them the form of vapor with hydrogen at elevated temperatures end at substantially atmospheric pressures in the presence of sulfur-immune Iuydrogenation catelysts.

The term, olkyl phenols, as used herein refers to ecicl-reectlng nydroxy aromatic compounds consisting essentially of ellsyl phenols and containing varying amounts of phenols and impuri- Allsyl phenols, sometsmes known as acid oils, ere obtained by extracting cracked mineral oil or coal-tar distillates with aqueous solutions of alkali metal hydroxide, end eoidiiying the alkaline extracts so obtained llllsyl have e number of important applications. For instance, they are used in the of ores, or in the manufacture of resins, alcohols, lzetones, etc, oz es anti-oxidants, disinfectants, selective solvents, etc, The 12resence of it "curl-ties such as sulfur compounds frequently impairs the usefulness oi the phenols for these purposes,

L733 has seen known to remove organic sulfur eonipoun "tom ellsyl phenols by hydrogenation at elevated temperatures and nressures. However, this process results in reduction of e considerable portion oi the phenols as Well es of tile compounds. when employing pressure Z tl'ie order of so or more atmospheres at efiec e lesuliurizatlon temioeretures, as heretolore considered necessary, as much as 2 of the phenols are destroyed.

Now, in accordance with our invention, We have found that elk l pnenols conteining suliurous ..ities can effectively lie desulfurised without substantial loss cl elisyl phenols by treetlng them the vapor phase with hydrogen at elevated temperatures and at substantially atmospheric pressure in the presence of sulfurimmune hydrogenation catalysts.

in order that this desuliurizetion under our conditions shall result in low sulfur content, it is necessary thet the major portion of the sulfur compounds, end preferably the entire amount, consist of thiopl'ienols, We have discovered that under our mild hydrogenation conditions, thicnlienols can Zoe converted substantially quen'titw tlvely to neutral hydrocarbons end readily sepsrelole sulfur compounds, such as H28. in con-' s, e producing sulfur content 23.371

phenols without substantial'loss in elkyl phenols themselves, it is very desirable to start out with an alkyl phenol mixture which contains as small an amount as possible of the sulfur compounds which are not reducible under our conditions.

Fortunately, most of the hydrogenation-resistant sulfur compounds are neutral, which compounds can be removed from slkyl phenol min tures at least in part by steaming or washing intensely the alkyl phenol mixtures while in scio tion of an aqueous alkali, almost any substantially water-insoluble good solvent for the sulfur compounds {which solvent is free from objectlom able elements) being suitable for the washing.

As is known, elkyl 1211811015 are normally recovered from cracked petroleum oil or coal-tor distilletes extraction aqueous solutions e2? caustic ellreli. Together with the acidic components contained in the distillate, a. considerable quantity of neutral oils also dissolved in the aqueous solution, l portion which are sulfur compounds the type difficult to hydro senate destructively, I-f wever, since these compounds are neutral ere erely held in the aqueous solution Toy virtue their solubility 55:. the elfazyl phenolstes, it is T-ossiole to remove them, or least a, substantial portion thereof, by the methods indicated shove, i. e., by intense steaming or washing with a suitable solvent sulfur compounds.

In order to recover from hydrocarbon distille' the largest portion the alkyl phenols contained therein, very strong solutions of aqueous metal hydroxides are usually employed L21 one extraction, i. e., aqueous solutions containing, 23oz,- example, se z, to se% most. The resulti eiuenolate solutions ere excellent solvents many of the stable neutral sulfur compounds, and in order to expel the latter more readily, it is often advantageous to dilute the phenolete solutions with water prior to washing or steaming them to reduce their solvent powers for the new rel sulfur compounds.

The catalysts that may be employed in accordance with our invention are those b vdrogenetion. catalysts which are substantially immune'to sullur poisoning. For example, it is known that such catalysts comprise metal oxygen compounds not reducible to metals under the reaction conditions or sulfidic compounds, said metal oxygen com in no case exceed 50 lbs.

as complex compounds ofphosphoric acid or silicic acid with molybdic acid or tungstic acid, as for example ammonium phosphomolybdate. Oxides of metals, when combined with acid in a non-complex form to form salts from which the acid cannotbe volatilized such as sulfates or silicates or phosphates, however, are not comprised 5 within the said term. As examples of metals, from which the oxidic or sulfidic compounds may be derived in the present case, may be mentioned copper, silver (the latter preferably in combination with molybdic acid, tungstic acid or vanadic acid), zinc, cadmium, tin, lead, vanadium, bismuth, chromium, molybdenum, tungsten, uranium, nickel and cobalt. But, also, the other heavy metals of the aforementioned groups of the periodic system are useful. The compounds obtainable-from salts of metal acids of the 5th or 6th group of the periodic system by complete or partial reduction with hydrogen sulflde have a specially advantageous catalytic ac- I tion.

These catalysts may contain activators such as alkaline earth metals, cesium oxide, thorium oxide, etc. The catalytic substances may be used in pill or pellet form or be deposited on a carrier such as activated alumina, pumice, carbon, silica gel, fuller's earth and the like.

The mol ratio of hydrogen employed to the phenolic feed may be between about 1:9 and 9:1 and preferably in a ratio between about 1:2 and 2:1.

' Depending on the catalyst used, the thiophenol content of the alkyl phenols and the alkyl phenol fraction employed, temperatures of treatment may vary from about 200 C. to 420 C. but in, some cases higher ,or lower temperatures may be employed. For most fractions of alkyl phenols, however, a temperature in the range of about 250 C. to 375 C. is sufllcient.

"To insure selective' reduction of the thiophenols without substantial loss of the alkyl phenols, the total pressure on the reactor should Since pressures but little above atmospheric may'cause substantial loss of the alkyl phenols, it is well to maintain in the reactor a pressure not to exceed 20 to 30 lbs., and preferably at about atmospheric pressure.

To enable substantial desulfurization at low pressures, the treatment of the' alkyl phenols with hydrogen must be carried out in the vapor 80 phase, for treatment in the liquid phase requires higher pressures of the order of 300 lbs. or higher, and results in loss of a portion of. the alkyl phenols. i

The following examples further illustrate our invention:

Example I m, of about 350 C. and a total pressure of 16 lbs. The volume of total feed per volume of catalyst per hour was maintained at about .43. Better than 98% of the albl phenols containing .057% sulfur were recovered.

Example II The vapors of analkyl phenolv fraction boiling in the range of 220 C. to 240 C. and containing about .6% sulfur were passed, together with hydrogen at 9. mol ratio of 1.6 hydrogen to 1 mol of the alkyl phenols, over an ammonium phosphomolybdate catalyst deposited on a grade-B activated alumina at a temperature of about 352 C. and a total pressure of about 16 lbs. The volume of feed per volume of catalyst per hour was maintained at about .46. Better than 98% of the alkyl phenols containing 045% sulfur were recovered.

Example III about .46. Better than 98% of the alkyl phenols containing .040% sulfur were recovered.

We claim as our invention:

1. A process for desulfurizing alkyl phenols containing sulfur-bearing impurities in the form of thiophenols which comprises treating said phenols in the vapor phase with hydrogen at a temperature between about 200 C. and about 420 C. and at a total pressure not to exceed 50 lbs. in the presence of a sulfur-immune hydrogenation catalyst.

2. The process of claim 1 in which the total pressure is substantially atmospheric.

. 3. The process of claim 1 in which a mol ratio of hydrogen to the phenolic feed is maintained between the limits of 1:9 and 9:1.

4. The process of ,claim 1 in which the temperature of treatment is about 275 C. to about 375 C.

5. The process of claim 1 in which the mol ratio of hydrogen to the phenolic feed is be-v tween the limits of 1:2 and 2:1.

6. A process for the desulrurization of alkyl phenols containing sulfur-bearing impurities in the form of thiophenols comprising treating said alkyl phenols in the vapor phase with hydrogen at a temperature between 200 C. and 420 C. under a total pressure of not more than 50 lbs. and in the presence of a catalyst comprising essentially ammonium phosphomolybdate.

'1. A process for the desulfurization of alkyl phenols containing sulfur-bearing impurities in the form of thiophenols comprising treating said alkyl phenols in the vapor phase with hydrogen at a temperature between 200 C. and 420 C. under a total pressure of not more than 50 lbs. and in the presence of a catalyst comprising essentially molybdenum sulfide.

8. A process for the desulfurization of alkyl phenols containing sulfur-bearing impurities in the form of thiophenols comprising treating said alkyl phenols in the vapor phase with hydrogen at a temperature between 200 C. and 420 C. under a total pressure of not more than 50 lbs. and in thepresence of a catalyst comprising essentially nickel sulfide.

9. A process for desulfurizing alkyl phenols containing sulfur in the form of neutral oils and thiophenols comprising the steps of removing said neutral oils from the mixture and contacting the resulting alkyl phenol fraction containing thiophenols in the vapor phase with hydrogen at a temperature between about 200 C. and 420 C. and a total pressure not to exceed 50 lbs. in the presence of a sulfur-immune hydrogenation catalyst.

10. A process for producing alkyl phenols of reduced sulfur content from hydrocarbon oils containing alkyi phenols and sulfur impurities in the form of thiophenols, comprising the'steps of extracting said alkyl phenols from said hydrocarbon oils with aqueous alkali metal hydroxide, removing neutral oils from the resulting extract, liberating the alkyl phenols from the extract so purified, and contacting said aikyl phenols in the vapor phase with hydrogen at a temperature between about 200 C. and 420 C. and at a total pressure not to exceed 50 lbs. in the presence of a sulfur-immune hydrogenation catalyst.

11. A process for reducing the sulfur content of alkyl phenols containing thiophenols which comprises treating said phenols in the vapor phase with hydrogen at a temperature between about 200 C. and about 420 C. and at a total pressure not substantially in excess of atmospheric in the presence of a sulfur-immune hydrogenation catalyst.

SAMUEL BENSON THOMAS. WILLIAM C. SMITH. 

